In an A375 melanoma cell line containing a b-RAFV600E mutation, Ulixertinib reduces the levels of phosphorylated ERK2 (pERK) and of the phosphorylation of the downstream kinase RSK (pRSK) with IC50 of 4.1/0.14 μM, respectively. Ulixertinib also inhibits A375 cell proliferation with IC50 of 180 nM.